TNF-α and interleukin 1 activate gastrin gene expression via MAPK- and PKC-dependent mechanisms

2001 ◽  
Vol 281 (6) ◽  
pp. G1405-G1412 ◽  
Author(s):  
T. Suzuki ◽  
E. Grand ◽  
C. Bowman ◽  
J. L. Merchant ◽  
A. Todisco ◽  
...  
Keyword(s):  
Gene Expression ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Kinase Inhibitor ◽  
Interleukin 1 ◽  
Mitogen Activated Protein Kinase ◽  
G Cells ◽  
Kinase C ◽  
Tnf Α ◽  
Mitogen Activated Protein

Helicobacter pyloriand proinflammatory cytokines have a direct stimulatory effect on gastrin release from isolated G cells, but little is known about the mechanism by which these factors regulate gastrin gene expression. We explored whether tumor necrosis factor (TNF)-α and interleukin (IL)-1 directly regulate gastrin gene expression and, if so, by what mechanism. TNF-α and IL-1 significantly increased gastrin mRNA in canine G cells to 181 ± 18% and 187 ± 28% of control, respectively, after 24 h of treatment. TNF-α and IL-1 stimulated gastrin promoter activity to a maximal level of 285 ± 12% and 415 ± 26% of control. PD-98059 (a mitogen-activated protein kinase kinase inhibitor), SB-202190 (a p38 kinase inhibitor), and GF-109203 (a protein kinase C inhibitor) inhibited the stimulatory action of both cytokines on the gastrin promoter. In conclusion, both cytokines can directly regulate gastrin gene expression via a mitogen-activated protein kinase- and protein kinase C-dependent mechanism. These data suggest that TNF-α and IL-1 may play a direct role in Helicobacter pylori-induced hypergastrinemia.

scholarly journals Rab6 is phosphorylated in thrombin-activated platelets by a protein kinase C-dependent mechanism: effects on GTP/GDP binding and cellular distribution

1999 ◽  
Vol 342 (2) ◽  
pp. 353-360 ◽  
Author(s):  
Michael L. FITZGERALD ◽  
Guy L. REED
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phorbol Esters ◽  
Kinase Inhibitor ◽  
Mitogen Activated Protein Kinase ◽  
Secretory Cells ◽  
Kinase C ◽  
Kd Values ◽  
Mitogen Activated Protein ◽  
Thrombin Activation

In platelets and other secretory cells, protein kinase C (PKC) plays a role in exocytosis stimulated by physiological extracellular signals, although its linkage to the secretory machinery is poorly understood. We investigated whether Rab6, a GTP-binding protein that fractionates with platelet α-granules, may be involved in linking these processes. We found that Rab6 contains two PKC consensus phosphorylation sites that are evolutionarily conserved. In platelets metabolically labelled with [32P]Pi, Rab6 phosphorylation was induced by phorbol esters or by thrombin. This phosphorylation was blocked by a specific PKC inhibitor (Ro-31-8220), but not by a p38 mitogen-activated protein kinase inhibitor (PD-169316). Physiological stimulation of platelets caused a PKC-dependent translocation of Rab6 from platelet particulate fractions, nearly doubling the fraction of Rab6 in the cytosol. A human Rab6 isoform (Rab6C) that is preferentially expressed in human platelet RNA was cloned and its phosphorylation by PKC was characterized. Rab6C incorporated up to 2 mol of [32P]Pi per mol of active protein. Rab6C bound GDP and GTP with Kd values of 113±12 and 119±27 nM respectively, and hydrolysed GTP at a rate of 100±15 μmol of GTP/mol of Rab6C per min. PKC phosphorylation of Rab6C increased the affinity for GTP by 3-fold, although it had lesser effects on GDP (1.6-fold). Phosphorylation did not alter the GTPase activity. In summary, thrombin activation of platelets leads to PKC-dependent phosphorylation of Rab6 and a translocation of Rab6 to the cytosol. We suggest that PKC phosphorylation may be an important mechanism through which Rab functional interactions in vesicle trafficking and secretion can be altered in response to an external stimulus.

CCK activates p90rsk in rat pancreatic acini through protein kinase C

1997 ◽  
Vol 272 (3) ◽  
pp. G401-G407 ◽  
Author(s):  
M. J. Bragado ◽  
A. Dabrowski ◽  
G. E. Groblewski ◽  
J. A. Williams
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Kinase Inhibitor ◽  
Threshold Concentration ◽  
Mitogen Activated Protein Kinase ◽  
Maximal Effect ◽  
Dependent Manner ◽  
Pancreatic Acini ◽  
Kinase C ◽  
Mitogen Activated Protein

The presence of the 90-kDa ribosomal S6 protein kinase (p90(rsk)) in isolated rat pancreatic acini was demonstrated by Western blotting and immunoprecipitation with anti-p90(rsk). Cholecystokinin (CCK) activated p90(rsk) activity in a time- and dose-dependent manner and increased its phosphorylation. The threshold concentration of CCK was 10 pM and the maximal effect was seen at 1 nM. An increase in p90(rsk) was observed 1 min after 1 nM CCK stimulation, reaching a maximum at 10 min, when p90(rsk) activity was increased 5.4-fold. Carbachol and bombesin, but not vasoactive intestinal peptide, also activated p90(rsk). CCK-induced activation of p90(rsk) appears to be mediated by protein kinase C (PKC), since 12-O-tetradecanoylphorbol-13-acetate increased p90(rsk) activity 5.3-fold. GF-109293X, a potent inhibitor of PKC, strongly inhibited CCK-evoked p90(rsk) activity. Treatment of acini with ionomycin or 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid had no effect, indicating that mobilization of intracellular Ca2+ by CCK is not important in p90(rsk) activation. Although there were some quantitative differences in the extent of inhibition, the specific inhibitors [rapamycin, wortmannin, mitogen-activated protein kinase (MAPK) kinase inhibitor PD98059, and GF-109293X] had parallel effects on p90(rsk) and p42(mapk) activities, consistent with a model in which p90(rsk) can be regulated in acini by MAPK.

CTP:phosphocholine cytidylyltransferase inhibition by ceramide via PKC-α, p38 MAPK, cPLA2, and 5-lipoxygenase

2001 ◽  
Vol 281 (1) ◽  
pp. L108-L118 ◽  
Author(s):  
Shanjana Awasthi ◽  
Jeevalatha Vivekananda ◽  
Vibhudutta Awasthi ◽  
Dolphin Smith ◽  
Richard J. King
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
De Novo ◽  
Cell Types ◽  
Companion Paper ◽  
Mitogen Activated Protein Kinase ◽  
Ctp:Phosphocholine Cytidylyltransferase ◽  
Kinase C ◽  
Tnf Α ◽  
Mitogen Activated Protein

In a companion paper (Vivekananda J, Smith D, and King RJ. Am J Physiol Lung Cell Mol Physiol 281: L98–L107, 2001), we demonstrated that tumor necrosis factor (TNF)-α inhibited the activity of CTP:phosphocholine cytidylyltransferase (CT), the rate-limiting enzyme in the de novo synthesis of phosphatidylcholine (PC), and that its actions were likely exerted through a metabolite of sphingomyelin. In this paper, we explore the signaling pathway employed by TNF-α using C2 ceramide as a cell-penetrating sphingolipid representative of the metabolites induced by TNF-α. We found that in H441 cells, as reported in other cell types, cytosolic phospholipase A2 (cPLA2) is activated by TNF-α. We also observed that the inhibiting action of C2ceramide on CT requires protein kinase C-α, p38 mitogen-activated protein kinase, and cPLA2. The actions of C2ceramide on CT activity can be duplicated by adding 2 μM lysoPC to these cells. Furthermore, we found that the effects of C2ceramide are dependent on 5-lipoxygenase but that cyclooxygenase II is unimportant. We hypothesize that CT activity is inhibited by the lysoPC generated as a consequence of the activation of cPLA2 by protein kinase C-α and p38 mitogen-activated protein kinase. The other product of the activation of cPLA2, arachidonic acid, is a substrate for the synthesis of leukotrienes, which raise intracellular Ca2+ levels and complete the activation of cPLA2.

Ca2+-independent synergistic augmentation of O2- production by FMLP and PMA in HL-60 cells

1998 ◽  
Vol 76 (10-11) ◽  
pp. 1024-1032 ◽  
Author(s):  
Katsuyoshi Tsukii ◽  
Norimichi Nakahata ◽  
Susumu Tsurufuji ◽  
Yasushi Ohizumi
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Superoxide Anion ◽  
Kinase Inhibitor ◽  
Chelating Agent ◽  
Mitogen Activated Protein Kinase ◽  
Protein Kinase C Inhibitors ◽  
Kinase C ◽  
Mitogen Activated Protein ◽  
Intracellular Ca

N-Formyl-Met-Leu-Phe (FMLP) and phorbol 12-myristate 13-acetate (PMA) caused a synergistic augmentation of superoxide anion (O2-) production in neutrophil-like HL-60 cells differentiated with dibutyryl cAMP. The present study was undertaken to investigate the mechanism of the synergistic augmentation of O2- production. FMLP increased intracellular free Ca2+ concentration ([Ca2+]i), which was slightly suppressed by PMA and completely inhibited by an intracellular Ca2+ chelating agent, O,Oprime-bis(2-aminophenyl)ethyleneglycol-N,N,Nprime,Nprime-tetraacetic acid tetraacetoxymethyl ester (BAPTA-AM). Although FMLP-induced O2- production was inhibited by BAPTA-AM, a major part of the synergistic augmentation of O2- production by FMLP and PMA remained after BAPTA-AM treatment, suggesting that a Ca2+-independent mechanism might be involved in the augmentation. FMLP and PMA caused an activation of phospholipase D (PLD) almost additively in a Ca2+-sensitive manner. The synergistic activation of mitogen-activated protein kinase (MAPK) was evoked by combined addition of PMA and FMLP in a BAPTA-AM resistant manner. However, PD98059, a MAPK kinase inhibitor, did not affect the synergistic augmentation of O2- production, although it potently inhibited the synergistic augmentation of tyrosine phosphorylation of MAPK. Wortmannin, a phosphatidylinositol 3-kinase inhibitor, inhibited FMLP-induced O2- production, but it did not inhibit the synergistic augmentation of O2- production by PMA and FMLP. In contrast, staurosporine and GF109203X, protein kinase C inhibitors, reduced the synergistic augmentation induced by PMA and FMLP. In addition, pertussis toxin (PT) abolished the synergistic augmentation of O2- production. It is concluded that the synergistic augmentation of O2- production induced by PMA and FMLP is mediated through a PT-sensitive G protein and a protein kinase C in a Ca2+-independent manner.Key words: superoxide anion, phorbol 12-myristate 13-acetate, N-formyl-Met-Leu-Phe, intracellular Ca2+ ions ; protein kinase C.

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